'67 L-79 fan belt question...

[Patrick T.]

I have a '67 L-79 engine in my car with no options. I have two questions. Does the emergency fan belt for the water pump go on the inside groove of the pulley, next to the engine or on the outside as shown in the picture below? Neither the AIM nor the '67 judging manual makes any mention of this item.

Next, did the midyear small blocks have lock washer's in the four mounting bolts or not? Again I have not seen any mention anywhere about lock washers in any publication and even the vendors sell the four mounting bolts but they don't come with lock washers.

Thanks for any clarifications in this matter. PT

[Rick S.]

Re: '67 L-79 fan belt question...

Patrick,
I have a 67 L-79 with PS. Are you asking if the bolts on the water pump have a lock washer or specifically the bolt for the alternator bracket/water pump as your arrow indicates? I have a lock washer as indicated by your arrow. Also my alt belt is on the inner pulley (closest to the engine) but then again I have PS. I have provided a bad picture for the lock washer.


Rick

[Joe R.]

Re: '67 L-79 fan belt question...

Hi Patrick:

The question of whether there should be a captive belt at all, and if so, whether it should be in the first or second groove, has been extensively debated in the archives, at least for 1966. I believe the issue pertains to 1967 as well.

It appears to me that your alternator may have the 3829387 pulley which is about 0.82 inches thick and 3.6 inches in diameter. Perhaps you could confirm these dimensions. Your alternator pulley is supposed to be a deep-groove puley that is separate from the fan. I can't quite tell from your photo if that is what you have.

If you have a 3829387 pulley and you are certain that this pulley is original to your car, that would imply (to me, at least) that the captive belt, if any, would have been installed in the second, outer groove. The 3829387 alternator pulley and the inside groove of the 3770245 WP pulley and the 3858533 crank pulley should line up pretty well. Assuming that you have the correct WP and crank pulleys, I would expect that if you put your alternator belt in the second, forward groove of the WP and crank pulleys, there would be a visible misalignment with the alternator.

Some people believe this configuration should have the 3871242 alternator pulley, which is about 1.3 inches thick and 3.6 inches in diameter. This pulley moves the belt about 0.5 inches farther forward, and probably lines up better with the second, forward groove of the WP and crank pulleys.

In summary, I believe that the ongoing debate about the proper position of the captive belt (if installed) is tied up with the question of which pulley is correct for the alternator.

I will go out on a limb and propose a theory that the original *intent* for the no-option L79 was to put a captive belt in the inner groove and the alternator belt in the second groove, in combination with the "thick" 3871242 alternator pulley. This would help explain why the alternator pulley was apparently changed to the "thin" 3829387 pulley when power steering was added, since the power steering belt occupies the second groove and the alternator belt had to be pushed back to the first groove (no captive belt was used with power steering).

There appears to be some debate about whether this configuration for the no-option L79 was ever used, or if it was, whether it was used consistently throughout the 1966-67 production. Maybe some others will chime in here.

[Joe L.]

Re: '67 L-79 fan belt question...

Hi Patrick:

The question of whether there should be a captive belt at all, and if so, whether it should be in the first or second groove, has been extensively debated in the archives, at least for 1966. I believe the issue pertains to 1967 as well.

It appears to me that your alternator may have the 3829387 pulley which is about 0.82 inches thick and 3.6 inches in diameter. Perhaps you could confirm these dimensions. Your alternator pulley is supposed to be a deep-groove puley that is separate from the fan. I can't quite tell from your photo if that is what you have.

If you have a 3829387 pulley and you are certain that this pulley is original to your car, that would imply (to me, at least) that the captive belt, if any, would have been installed in the second, outer groove. The 3829387 alternator pulley and the inside groove of the 3770245 WP pulley and the 3858533 crank pulley should line up pretty well. Assuming that you have the correct WP and crank pulleys, I would expect that if you put your alternator belt in the second, forward groove of the WP and crank pulleys, there would be a visible misalignment with the alternator.

Some people believe this configuration should have the 3871242 alternator pulley, which is about 1.3 inches thick and 3.6 inches in diameter. This pulley moves the belt about 0.5 inches farther forward, and probably lines up better with the second, forward groove of the WP and crank pulleys.

In summary, I believe that the ongoing debate about the proper position of the captive belt (if installed) is tied up with the question of which pulley is correct for the alternator.

I will go out on a limb and propose a theory that the original *intent* for the no-option L79 was to put a captive belt in the inner groove and the alternator belt in the second groove, in combination with the "thick" 3871242 alternator pulley. This would help explain why the alternator pulley was apparently changed to the "thin" 3829387 pulley when power steering was added, since the power steering belt occupies the second groove and the alternator belt had to be pushed back to the first groove (no captive belt was used with power steering).

There appears to be some debate about whether this configuration for the no-option L79 was ever used, or if it was, whether it was used consistently throughout the 1966-67 production. Maybe some others will chime in here.

Joe and Patrick-----


The pulley on Patrick's alternator is not a GM #3829387. It looks to me like it's either a GM #3909815 or 3909817. These are 2.80" ('815') and 2.65" ('817') fabricated steel pullies which are integral with the fan. I don't think that either of these pullies was ever originally used for an L-79.

The L-79 without N-40 or C-60 should use pulley GM #3871242. This is a machined steel pulley of 3-5/8" OD with a "built-in spacer". The effect of the spacer would be to move the pulley outward one groove so that the alternator belt would line up with the outer groove of the waterpump pulley. The inner groove would then accommodate the captive belt. Whether a captive belt was ever originally installed I don't know, for sure, but I expect it was.

[Wayne M.]

Re: '67 L-79 fan belt question...

Patrick, Joe(s) et al:

Sure looks line a "245" w.pump pulley (can even see the spot weld bead and pressed-on outer groove assy). Patrick; is that a pulley flange reinforcement on the OUTSIDE that I'm seeing ?

Agree with Joe that pic shows a small alternator pulley, not consistent with a "245" and L79 (no C60, no P/S). Unfortunately I don't have a '67 AIM or a similar car to comment on belt arrangement. Must say that I thought, of all C2's, only the '65 L78 BB had the captive idler belt in the forward crank and w.pump pulley grooves. Long Island catalog has sketches of pulley/belt arrangements for all C2 combinations, and it seems to agreee with how Patrick has his.

[Joe R.]

Re: '67 L-79 fan belt question...

Hi Joe:

I thought the pulley in Patrick's photo didn't look quite deep enough, but I wasn't sure. I also could not tell if it was separate from the fan.

One thing that interests me about the comparison of the 3829387 and the 3871242 alternator pulleys is that the difference in position of the belt groove is about 0.5 inches, while the distance between the groove centerlines on the 3770245 WP pulley is about 0.75 inches. While I think the 3871242 would look visibly misaligned if used with the inside groove of the WP pulley, it appears that it would also not be perfectly aligned with the second groove. Perhaps GM determined that perfect alignment was not necessary.

I have the impression that the 3871242 was originally developed prior to 1966 for some other applications, so maybe GM decided that the existing part was "close enough" to use in the no-option L79 application for 1966-67.

[Patrick T.]

Re: '67 L-79 fan belt question...

Thanks for your comments, I hate to open up this can of worms again. I believe all the pulleys on the car are original. The '67 Judging Guide specifies that an L-79 without P/S or A/C should have a one piece fan and pulley combination with a gray phosphate finish part #3909815, which is what I have. There are so many combinations of pulleys and RPO's that dictate where the fan belt(s) should go, I won't even try to get into that.

All I can tell you is that from the picture below, the captive belt is on the second groove next to the radiator, while the alternator belt is in the first groove next to the engine. Notice how the belt lines up perfectly with the first groove on the water pump pulley. If I had these reversed, then the alternator belt would not line up with the second groove and might even fly off.

I guess I'll just leave it as is and get it judged and see what happens. Again, thanks for your input. PT

[Joe L.]

Re: '67 L-79 fan belt question...

Thanks for your comments, I hate to open up this can of worms again. I believe all the pulleys on the car are original. The '67 Judging Guide specifies that an L-79 without P/S or A/C should have a one piece fan and pulley combination with a gray phosphate finish part #3909815, which is what I have. There are so many combinations of pulleys and RPO's that dictate where the fan belt(s) should go, I won't even try to get into that.

All I can tell you is that from the picture below, the captive belt is on the second groove next to the radiator, while the alternator belt is in the first groove next to the engine. Notice how the belt lines up perfectly with the first groove on the water pump pulley. If I had these reversed, then the alternator belt would not line up with the second groove and might even fly off.

I guess I'll just leave it as is and get it judged and see what happens. Again, thanks for your input. PT

Patrick------


Personally, I think the JG is incorrect on this one if it states that L-79 w/o N-40 and C-60 used the stamped steel pulley. There are 2 reasons I think so.

First, I can't find any GM information that indicates that either of the 2 stamped steel pullies were used on an L-79.

Second, both of the stamped steel alternator pullies I previously mentioned are standard groove depth pullies. The GM #3770245 waterpump pulley and GM #3858533 crank pulley used for your application are deep groove pullies. It seems unlikely to me that GM would have used the standard groove alternator pulley with the other deep groove pullies. They did do this for some SHP with C-60 applications, but I just can't see them doing it with other applications. A standard groove alternator pulley would pretty much negate the benefit of using deep groove pullies for the waterpump and crank.

One other thing: your 3770245 waterpump pulley appears to be painted. My recollection is that most original 3770245 pullies were black phosphate-finished, although it's very possible that some were painted. Later SERVICE pullies were definitely painted. This may or may not imply something in your case.

As far as how the car will judge, as-is, it should be fine if the JG states that it should have the alternator pulley configuration it has, whether or not that configuration is actually correct.

[Patrick T.]

Re: '67 L-79 fan belt question...

Just for the record, here is a scan out of the 4th edition '67 Judging Guide listings for all of the combinations of belts and pulley's for the base engine and L-79 small block engines. My alternator pulley is dark gray phosphate and not painted. PT

[Joe L.]

Re: '67 L-79 fan belt question...

Just for the record, here is a scan out of the 4th edition '67 Judging Guide listings for all of the combinations of belts and pulley's for the base engine and L-79 small block engines. My alternator pulley is dark gray phosphate and not painted. PT

Patrick-----


I didn't doubt that the JG stated what you said. I just feel it's incorrect for the L-79 application. I may be right or I may be wrong. That's my opinion, though.

Your alternator pulley is definitely black phosphate-finished; no doubt about that, at all. I think that most, if not all, examples of the 3909815 pulley were black phosphate-finished right up until the time it was discontinued in May, 1981. However, as far as finish is concerned, the pulley I was referring to in my previous post is the waterpump pulley. Early examples of this pulley that I've seen are black phosphate finished. However, as I mentioned, I don't know that all were. Later SERVICE are definitely painted, though.